With the rapid development of the fourth generation (4G) of mobile communication technology, high-speed Internet access speed and convenient network services have been achieved. If users want to enjoy good services brought by 4G, they must buy a mobile phone which supports the LTE standard. According to the survey, there are not many users buying LTE mobile phones currently mainly due to the following aspects: first, LTE mobile phones are relatively expensive so that the scope of its applicable group is smaller; second, the users who just change to use 3G mobile phones will spend efforts and waste resources, to a certain extent, in changing mobile phones once again. Thus, an urgent problem to be solved is how to enable non-LTE mobile phones such as 2G or 3G mobile phones to access the LTE network and then enable their users to enjoy the 4G high-speed service without changing to LTE mobile phones.